CC BY
15
Nutfullaeva Lobar Nurullaevna, senior lecturer,
Bukhara Engineering and Technology Institute, Artikbaeva Nozima Mumindjanovna, senior lecturer, Bakhritdinova Dilrabo Amanbaevna, senior lecturer, Shin Illarion Georgievich, doctor of technical sciences, professor, Tashpulatov Salikh Shukurovich, doctor of technical sciences, professor, Tashkent Institute of Textile and Light Industry, Murodov Tahir Bakhramovich, candidate of technical sciences, associate professor, Tashkent Institute of Textile and Light Industry E-mail: [email protected]
INVESTIGATION OF FORMATION CONDITIONS PACKAGE AND ENSURING PILLARITY OF PILLOWS FROM COMPOSITE MATERIALS
Abstract: In this chapter of the dissertation work the questions of the use of composite materials that meet the modern requirements of industrial production, its varieties, composition, their properties, methods of obtaining composite materials, the effectiveness of their use in production conditions, including the use in the working bodies (cushions) of equipment for wet-heat treatment of parts of garments. Also given are information on the methods and mechanisms for forming a package of working elements (cushions) for wet-heat processing of garments when using composite materials.
Keywords: Composite materials, industry, composition, properties, efficiency, cushions, working elements, wet-heat treatment.
When modernizing the technology of making garments, it is necessary to save energy, raw materials, their secondary use, reduce the laboriousness of manufacturing products, solve problems aimed at expanding the range of products and improving its quality on equipment where parts and assemblies are made of new polymer composite materials.
The development of components or components of equipment from composite materials is not only related to its use in shaping and wet-heat processing of garments, but also to the formation of its structure and physical and mechanical characteristics, performed at the design stage of composite materials. Thus, the development of parts of equipment, for example, cushion press equipment for wet-heat treatment of composite materials is a promising and clear example of the triunity - the material, design and technology, because in the design and manufacturing processes provide the basic properties of the composite material. The greatest efficiency in the use of composite materials is achieved in solving problems of reducing metal consumption, energy intensity, improving
strength, durability and reliability (specific strength), reducing weight and cost of structures, increasing technological productivity in combination with flexibility and versatility. For example, the use of composites in the production of aircraft is growing. Whereas in the production of Boeing 747 aircraft in 1969 only 1% of the components were made from composites, in the Voing 787 plane the proportion of composite parts is more than 50%. The use of composites allows the creation of more sophisticated aerodynamic designs and reduces the weight of the aircraft, which leads to savings of 4-6% of fuel [1]. The same example can be given endlessly in the automotive industry, in the activities of the management of housing and communal services, etc.
From the analysis of [1] it follows that the most effective and promising way of forming a package of the surface shell is a method based on deformation of the network structure.
Studies [1] showed that the shape attached to parts due to deformation of the network structure is not sufficiently stable, and requires additional fixing. The fixing of the bulk surface is
Section 12. Technical science
carried out mainly by means of edges and additional gaskets. Edge and additional gaskets do not provide fixation of the required surface and interfere with the process of forming the bag. The same mechanism can also be used for the formation of a rational package of cushion press equipment for wet-heat treatment of composite materials.
When analyzing the structure of deformed tissue sections [1] consisting of the main tissue and located at some angle of the adhesive pad, it is noted that a rectangular cell of the network structure of one system intersecting with threads of another system is divided into inactive triangles that limit the mobility of the packets.
It follows that the formed such a package system acquires high form stability and low mobility of the structure. Taking this into account, thus forming a package for any products, it is possible to achieve optimal properties (for transfer from anisotropic to isotropic state) necessary for the uninterrupted functioning of products made of composite materials, further in the dissertation work the possibilities of manufacturing press cushions for wet-heat treatment are considered.
The actual direction in improving the quality of garments is the improvement of the process and equipment for wet-heat treatment (WHT). The importance of the WHT is predetermined by the need for its use at various stages of the technological process of making garments (preliminary giving some parts or parts of details to the spatial form, interoperative WHT parts and assemblies, final finishing, etc.), which makes it easy to perform subsequent operations and generally effects on the quality of garments. The possibility of applying WHT for the manufacture of sewing articles by molding [1], which excludes multi-operation transitions and the costs of various resources associated with them, imposes a number of important requirements for the construction of working bodies - cushions of press equipment. First of all, this is due to the fact that all expenses for the design, manufacture and operation of airbags directly affect the cost of products, which should also be competitive in terms of quality and cost.
The existing designs of the working bodies of presses for the WTO, requires improvement, as they do not fully provide the final molding of products in accordance with the specified model, metal and with a large weight, energy-intensive, high construction cost. With a view to eliminating these drawbacks, a technology has been developed for manufacturing cushions for press equipment.
A package of multilayered composite material was used to make the pillows. When forming the package, it was taken into account that any fabric a priori possesses anisotropic properties, which under operating conditions under the influence of technological forces undergo non-uniform deformations in a plane normal to the acting load. Due to the inhomo-
geneous strain, a stress state arises that differs by different
values of the main normal stresses S1, S2 and S3. In the case of a plane stress state, when S3 = 0 (in the case of neglecting the thickness of the deformed body), we have ^ ^ S2.
In the case of creating a stack of multilayer composite material, it is important to arrange the layers relative to one another at a certain fixed angle, i. E. the angle between the strands of the system (layers) will be assumed to be ft = 15 o, 30 o, 45 o, 60 o, 75 o and 90 o. In this way, a multilayer composite package can be used to determine the dependence of the strength parameters on the orientation of the layers of the package.
Further rotation of the layers relative to the previous layer repeats the similar arrangement of the filaments, but in the opposite direction.
Such an arrangement in the stack of layers of the composite material with a directed fiber orientation can create the prerequisites for providing conditions for equal resistance of any point of the loaded surface. This assumption is based on the fact that, in reality, in a networked multi-layered bag system, the filaments are positioned so close together that at any loaded point of the bag has the same picture of the arrangement of the warp threads. Therefore, the local deformation process, caused by biaxial stretching and taking place during the pressing of parts of clothing with the help of pillows in the WHT, should occur with the same degree of intensity. This will be possible if the surface layer of the cushions from the package of composite material is deformed elastically equally in all directions, i.e. showing the acquired isotropy and, as is customary in metal science, the quasi-isotropy of the material.
When the plane stressed state (S3 = 0) is a particular case of a volumetric stress state, the principal stresses S1 and S2 are
E
determined by the formulas: ^ =-j-(£i + lJ£2 )
E ^
82 =--2 (£i +№) (1)
1
where the relative deformations 1 and 2 are respectively equal
- _ ^L -_ E E
5
A
E
(2)
5 5 5 e1 = — -m— 1 E E
2
It is important to note that the elastic characteristics of structural materials (E - modulus of elasticity, y -coefficient of a punch) are applicable only for isotropic bodies. The elastic properties of anisotropic bodies (for example, single crystals) are characterized by a much larger number of constants - from 3 in the simplest case to 21 in the case of the most general form of anisotropy [2].
In the annex to textile materials, as shown by A. Solov'ev [3], the elastic modulus E should be considered as a modulus of relative rigidity (to the cross-sectional area S)
E = P/(eS), where, P - force; s - relative deformation.
The ratio P/e is usually called the stiffness of the material. Fibers and threads often undergo short-term and small stretches. So, if you give the fibers and yarns small elongations (up to 1%) and for a short (a few seconds) time, then the deformation in most of their species will be almost completely reversible and mostly elastic. The definition of modules under such conditions is completely correct and similar modules are often called initial ones, since they were obtained under the initial conditions of stretching. Such a module can be used to calculate the relationship between strain and stress in accordance with Hooke's law.
Thus, giving solid bodies isotropic properties makes it possible to use the mathematical apparatus of the theory of elasticity and plasticity to solve important applied problems to ensure the strength and load-bearing capacity of critical machine parts.
In accordance with the design scheme of the grid multilayer pack system, the forces in the rods act at different angles $ and to determine the normal stress 5 it is necessary to take into account the constant cross-sectional area of the yarn (rod). This problem can be simplified by considering a constant tensile load P within one rod, but causing different stresses (normal 8, and tangential t) in the plane of the section drawn at the same angles $ = 15 ", 30 ", ... 75 o. The position of the oblique section in the rod is determined by the angle $ between the normal i to it and the x axis.
Because of the uniformity of the stress state in the rod, the stresses Pi along the oblique section are uniformly distributed, and they are parallel to the x axis. The area of the inclined section
where the relative deformations 1 and 2 are respectively equal F = F /cos p
From the equilibrium condition of the distinguished part
EX = -P + pF/cos P= 0
P
It follows P =— cos B either P =S cos B
• f •
(3)
Projecting P, on the normal to the oblique section and its plane, we obtained
5 .
5i=5cos p t=— sin2^
(4)
Analysis of the dependences (2) shows that the normal stresses reach the greatest value at $ = 0 (in cross sections);
tangential stresses reach the greatest value at P = 450, with t max = < / 2; The normal stresses acting in this section (p= 45°) are [a]p = 450 =a /2.
To analyze the stress state at the point of the rod section drawn at different angles $, it is expedient to calculate the values of cos2$ and sin2$, which for a single external stress a characterize the regularity of the variation of the normal ai and tangential stresses t..
Experimental studies of deformations of the network structure of the tissue model were carried out using relief strings. Of these, meshes were made of 12 cells with sides of 20 mm. For preliminary deformation of the grid cells, the strings were fastened together so that the longitudinal strings were positioned relative to the transverse strings at an angle a = 45 "(network angle). Further, the transverse strings of one grid were fastened with strong threads with transverse strings of another grid at angles $ equal to 15 " and 30 ". Thus, a similarity of a composite material was created when all the reinforcing elements were fixed with the filler.
In this case, the normal stress a almost twice exceeds the tangential stresses t. Therefore, the destructive process is initiated by the action of normal stresses, which mainly cause brittle failure and plastic shear of the material is minimal. With an increase in the angle $ from 15 to 30 the tangential stress, which is responsible for the plastic flow of structural materials, increases noticeably, and therefore it more intensively resists destruction until the exhaustion of the plasticity is exhausted. The most pronounced plastic deformations occur in the plane at an angle of 45 " to the axis of the tensile (compressible) samples, forming the well-known Luders-Chernov lines.
Thus, on the basis ofthe foregoing, it can be concluded that an effective technology and design of a package of multi-layer composite material of a press tool for WTO components of garments has been created, differ in that it provides isotropic properties. Due to this, uniform strength, equal resistance to elastic deformations ands better retention of a given shape of the pillows are achieved. Therefore, the design of the cushions from the given composite material is able to significantly increase the efficiency of the press equipment for the WTO through the quality production of the details of clothing by molding.
References:
1. Tashpulatov S. Sh. Development of a highly efficient resource-saving technology for the manufacture of garments: Author's abstract. diss.....doc.tech.sc. - Tashkent: TITLP. 2008.- 42 p.
2. Filin A. P. Applied mechanics of a solid deformable body. in 3-t.- M.: Science, 1978.- T. 1.- P. 230-237.
3. Kukin G. N., Soloviev N. I., Koblyakov A. I. Textile materials science.- M.: Legpromtizdat. 1989.- 352 p.
